1. Field of the Invention
This invention relates to an electric circuit breaker of a type comprising: a first hollow stationary contact element; a second hollow movable contact element; a third movable tubular contact element for connecting the first and second contact elements in the on position of the breaker; and a piston-cylinder arrangement for providing a flow of quenching medium to quench the arc drawing between such contacts.
2. Description of the Prior Art
In circuit breakers of the above type, the quenching gas flow is determined by the gas throughput of both the first and second hollow contacts or nozzles. The radial flow component of the quenching gas, which is directed toward the contacts and blasts the arc, increases in strength the closer the contacts are together. As a result, closely adjacent contacts permit the interruption of larger currents. On the other hand, when in the open condition, the breaker must be able to safely withstand switching and lightning surges, as well as higher ac voltages, (phase-to-phase voltage, phase opposition) which may be substantially higher than the crest value of the nominal voltage. This, in turn, requires that the distance between the contacts be as large as possible. To meet these requirements for high voltage during the open or off condition of the breaker and large current during the quenching condition thereof, which requirements contradict each other as far as the distance beween the first and second contacts is concerned, the movable second contact is moved between a first or quenching position during the quenching condition and a second or separation position during the open condition of the breaker.
More particularly, such a circuit breaker configuration is disclosed in the German Offenlegungsschrift No. 19 66 973. In this breaker, the movement of the second contact element is controlled by a reversing lever linkage which is rigidly coupled to the breaker drive. However, such a reversing or toggle lever linkage is very expensive, particularly for power circuit breakers with only a single gap, and requires a considerable amount of space.
It is, therefore, an object of the present invention to provide a circuit breaker of the above type wherein an inexpensive and compact arrangement is employed for movement of the movable second contact.